This invention relates to dental scaling instruments, or curettes, more particularly to dental scalers which are uniquely useful to remove food debris and plaque from the transmucosal region of implant abutments made of relatively soft materials such as titanium and alloys of titanium or gold that are in use to support dental restorations on dental implant fixtures.
Dental scaling instruments are used to remove food debris, plaque and calculus from natural teeth in the vicinity of the gum line as well as above and below the gum line. Scaling is the scraping motion applied to a hard surface to remove debris. Instruments used to perform this operation on natural teeth are made of materials which are hard and rigid enough to remove calculus and plaque from the surfaces of natural tooth enamel and the tooth root (cementum) and flexible enough to maintain contact with those surfaces while being manipulated by the clinician or dental hygienist. In the present state of the art of dentistry stainless steel in the form of a flexible hook-like extension from a rigid handle is used to fashion dental scaling instruments. Various hook configurations and shapes are in use, among them being, but not limited to, the "universal" and the "Gracey" shapes. Hard materials like stainless steel in the currently available shapes are suitable to scale away plaque and calculus from the natural dentition without scratching or damaging the natural enamel. Natural tooth enamel is harder than stainless steel and has a smoother surface. These characteristics prevent hard materials such as stainless steel from abrading the enamel. The natural root surface however is softer (cementum) and scaling of roots is purposely done to smooth this surface.
Modern dentistry includes the new technique of implantology. In this new technique a dental implant fixture is placed in the jawbone of a patient in a location where the patient is edentulous, and an artificial tooth is supported on that implant fixture. To achieve this support a component, commonly called an abutment, which extends from the implant fixture in bone through the patient's gum, is used to unite the tooth or crown to the fixture. The portion of the abutment which exits the gum is subject to the same rigors as a natural tooth at the gum line; that is, it, too, is exposed to calculus and plaque, and a program of dental hygiene is imperative to maintain the health of the gums and the jawbone where the implant fixture is installed. In fact, such a hygiene program may be more necessary to the maintenance of an implant-supported dental restoration than for the maintenance of healthy natural teeth for the reason that if plaque and calculus are permitted to collect on the abutment and under the surface of the surrounding gingiva, bacteria will eventually attack the bone surrounding or in contact with the implant fixture, and the union between the implant fixture and the bone will eventually fail.
Titanium and its dilute alloy TiA16-4V are at the present time the materials of choice for fabrication of dental implant fixture and the components used with them, including abutments. Titanium is relatively soft compared with natural tooth enamel. The hard materials (e.g. stainless steel) presently used to make dental scaling instruments are found to scratch titanium and its dilute alloy, providing sites for bacteria to take residence and proliferate. Scratched and roughened surfaces will collect even more plaque and calculus than a smooth surface. Existing dental scaling instruments are therefore not useful to maintain dental restorations supported on dental implant fixtures. A need exists for a dental scaling instrument that can be used in a program of maintenance hygiene for a dental-implant supported restoration.
Dental scaling instruments for this purpose have been proposed using plastics materials in place of the stainless steel that is now in use, but the plastics materials that have been tried have not been satisfactory for a variety of reasons. If made thin enough to fit between and around the teeth and their supporting abutments and the gums they have been found to be too flexible to remove harder calculus deposits, or so rigid a plastic that they are brittle and break in use. If made thick enough to have adequate flexibility and strength they are too thick to fit between and around the teeth and abutments and gums being treated. Dental scaling instruments coated with titanium and titanium nitride have also been proposed, and these have been shown to scratch titanium. There is a continuing need for a dental scaling instrument useful in a program of hygiene for dental restorations supported on dental implant fixture which will have enough rigidity to remove calculus as well as plaque, will be fine enough in design to allow subgingival scaling, and will be soft enough not to scratch or abrade titanium or other abutment material. The present invention provides such instruments.